Optical modules such as semiconductor laser (LD) modules having a semiconductor laser fitted at an end of an optical fiber are subjected to screening (judgment on pass or fail) after they are manufactured, the screening including tests such as temperature cycling test, burn-in test, etc., and those which fail to meet a predetermined criterion are removed while those which meet the criterion are shipped as final products.
Conventionally, characteristics of a semiconductor laser (hereinafter referred to as “LD”) included in an optical module, such as an optical output (L) as a function of operating current (I) (hereinafter referred to simply as “I-L characteristic”), an operating voltage (V), an monitor current (Im), etc. are evaluated, for example, in the following manner:
Optical modules are fitted to an inspection apparatus one by one. The above-mentioned characteristics of the optical modules are measured, and then the optical modules are detached from the inspection apparatus. Then, temperature cycles are applied to the optical modules in an environmental chamber, thereafter the optical modules are taken out of the environmental chamber, fitted again to the inspection apparatus one by one, and the characteristics of the optical modules are measured.
And based on the measurement results of the characteristics of the optical modules obtained before and after the application of temperature cycles, the rate of change in each characteristic is evaluated. Thus, conventionally, optical modules had to be fitted to and detached from the inspection apparatus each time they are tested, and hence, it is cumbersome to inspect a large number of optical modules.
Further, in the above-described method of inspecting optical modules, since each optical module needs to have its measured data recorded with one-to-one correspondence between the measured data obtained before and after application of temperature cycles on each measurement item, there is a problem that the larger the number of optical modules, the more cumbersome data management becomes.
In this way, inspecting a large number of optical modules requires not only a long tact time for inspection or screening but also cumbersome works to be done of data-processing and of screening on the basis of the processed data.
Thus, there is a demand for an efficient inspection method and an apparatus, capable of simultaneously inspecting a plurality of optical modules in a short time.
Further, in simultaneously inspecting a plurality of optical modules, there also was a problematic factor diminishing efficiency of the inspection, that redundant-length portions of optical fibers extending from the plurality of optical modules got tangled and hindered the inspection.